Tundra:   Tundra is found at high latitudes, adjacent to ice margins, where insolation is low.  Tundra is the youngest of all biomes as it was formed after the retreat of glaciers 10000 years ago.  Lack of light and rainfall mean (25 cm per year) that rates of photosynthesis and productivity are low. Large part of the year, water can be locked away in permafrost, a layer of permanently frozen soil below 0.5–1 m.